CN101185184A - Electrodes for nonaqueous electrolyte secondary batteries, nonaqueous electrolyte secondary batteries, and automobiles, electric tools, or stationary equipment incorporating the nonaqueous electrolyte secondary batteries - Google Patents

Abstract

The non-aqueous electrolyte secondary battery of the present invention uses a positive electrode, wherein the positive electrode active material contains a lithium-containing composite oxide, the peak micropore diameter of the positive electrode mixture layer is 0.7 μm or less, and the positive electrode mixture layer is 0.7 μm or less per unit of the positive electrode active material. The micropore volume of the weight is 0.05cm ³ /g～0.3cm ³ /g; or use a kind of negative electrode, wherein, the negative electrode active material contains carbonaceous material, the peak micropore diameter of the negative electrode mixture layer is 0.7μm or less, the negative electrode mixture layer The pore volume per unit weight of the negative electrode active material is 0.2 cm ³ /g to ^{0.4 cm 3} /g.

Description

Electrodes for nonaqueous electrolyte secondary batteries, nonaqueous electrolyte secondary batteries, and automobiles, electric tools, or stationary equipment incorporating the nonaqueous electrolyte secondary batteries

technical field

The present invention relates to a nonaqueous electrolyte secondary battery suitable for use as a power source for driving vehicles such as electric vehicles and hybrid vehicles, electric tools, and stationary equipment, and more specifically, relates to electrodes for nonaqueous electrolyte secondary batteries. Control of pore volume distribution.

Background technique

In recent years, the miniaturization and weight reduction of electronic equipment are rapidly progressing. Along with this, there is an increasing demand for smaller, lighter, and higher capacity batteries used as power supplies for devices. At present, non-aqueous electrolyte secondary batteries with high energy density such as lithium secondary batteries have reached the level of practical use. In the automotive field, the development of electric vehicles and hybrid vehicles (vehicles that combine an engine and a secondary battery) are actively being developed.

A high level of heavy-load pulse input and output characteristics is required for secondary batteries mounted on electric vehicles or hybrid vehicles. For example, in the case of a hybrid car, the secondary battery is required to provide boost to the engine when the car starts, starts, and accelerates. Therefore, it is required to have the performance of outputting large energy in a short time of about several seconds to ten seconds. On the other hand, when the vehicle is decelerating, regenerative energy must be efficiently recovered to the secondary battery.

It is assumed that EVs and HEVs will be used around the world. It is assumed that a secondary battery mounted on a vehicle is exposed to a wide range of ambient temperatures ranging from high temperature to low temperature, so it is necessary to have good battery characteristics in a wide temperature range. As the low temperature range, an extremely low temperature environment of -10°C to -30°C is assumed. Even in such an environment, a high level of input and output characteristics is necessary.

In order to obtain a secondary battery having high input-output characteristics, it is necessary to reduce the internal impedance of the battery as much as possible. Therefore, it was proposed (i) to increase the area of the plate and expand the charge-discharge reaction area by making the plate thinner and longer, thereby reducing the battery impedance; (ii) to reduce the active material filling density of the plate and increase Porosity, so that the method of improving the charge and discharge reaction; and (iii) the method of improving the conductivity of the non-aqueous electrolyte, etc. However, when increasing plate area, and increasing plate porosity were tested, the energy density of the battery decreased.

In order to increase the energy density of the battery, it is necessary to use a plate filled with active materials at a high density (ie, a low-porosity plate). However, if a low-porosity plate is used, ion diffusivity in the plate tends to decrease. As a result, when performing continuous heavy-load charge and discharge, the ions cannot move smoothly, and the ion concentration in the electrode plate gradually decreases, so that a stable charge and discharge reaction cannot be performed.

Therefore, Patent Document 1 proposes a method in which the porosity of the positive electrode of the non-aqueous electrolyte secondary battery is set to 25% or less, and the solute concentration of the non-aqueous electrolyte is higher than the concentration giving the peak conductivity. This solution intends to maintain the ion concentration in the plate by increasing the solute concentration (ie ion concentration) of the non-aqueous electrolyte, thereby improving the charge and discharge reaction.

According to the proposal of Patent Document 1, in order to continuously obtain sufficient heavy-load charge-discharge characteristics, the solute concentration of the non-aqueous electrolyte needs to be about 1.5 mol/dm ³ or more. However, when the solute concentration increases beyond the concentration giving the conductivity peak, the impedance of the nonaqueous electrolyte increases. The improvement of the solute concentration is effective in the case of continuous charge and discharge for a long time, but a voltage drop due to the impedance of the nonaqueous electrolyte occurs in the case of short-time pulse charge and discharge. As a result, variations in battery voltage increase and pulse output characteristics deteriorate. In addition, in the case of using a non-aqueous electrolyte with a high solute concentration, it may lead to an increase in material cost.

Patent Document 1: JP-A-2003-173821

Contents of the invention

In view of the above circumstances, the present invention aims to obtain favorable battery characteristics by controlling the pore volume distribution of an electrode for a nonaqueous electrolyte secondary battery.

The invention relates to a positive electrode for a non-aqueous electrolyte secondary battery, which has a positive electrode collector and a positive electrode mixture layer attached thereon, wherein the positive electrode mixture layer contains a positive electrode active material, and the positive electrode active material contains a lithium-containing composite oxide. The peak pore diameter of the positive electrode mixture layer is 0.7 μm or less, and the pore volume per unit weight of the positive electrode mixture layer relative to the positive electrode active material is 0.05 cm ³ /g to 0.3 cm ³ /g. The peak pore diameter of the positive electrode mixture layer is preferably 0.5 μm or less.

The present invention also relates to a negative electrode for a non-aqueous electrolyte secondary battery, which has a negative electrode current collector and a negative electrode mixture layer attached thereto, wherein the negative electrode mixture layer contains a negative electrode active material, the negative electrode active material contains a carbon material, and the negative electrode The peak pore diameter of the mixture layer is 0.7 μm or less, and the pore volume per unit weight of the negative electrode mixture layer relative to the negative electrode active material is 0.2 cm ³ /g to 0.4 ^{cm 3} /g. The peak pore diameter of the negative electrode mixture layer is preferably 0.5 μm or less.

The present invention also relates to a non-aqueous electrolyte secondary battery (battery A), which has a positive electrode, a negative electrode and a non-aqueous electrolyte, wherein the positive electrode has a positive electrode current collector and a positive electrode mixture layer attached thereon, and the positive electrode mixture layer contains a positive electrode The active material, the positive electrode active material contains lithium-containing composite oxide, the peak pore diameter of the positive electrode mixture layer is 0.7 μm or less, and the micropore volume of the positive electrode mixture layer relative to the positive electrode active material per unit weight is 0.05 cm ³ /g～0.3 cm ³ /g.

The present invention also relates to a non-aqueous electrolyte secondary battery (battery B), which has a positive pole, a negative pole and a non-aqueous electrolyte, wherein the negative pole has a negative electrode current collector and a negative electrode mixture layer attached thereon, and the negative electrode mixture layer contains a negative electrode The active material, the negative electrode active material contains carbon materials, the peak pore diameter of the negative electrode mixture layer is 0.7 μm or less, and the micropore volume per unit weight of the negative electrode mixture layer relative to the negative electrode active material is 0.2 cm ³ /g～0.4 cm ³ /g.

The present invention also relates to a nonaqueous electrolyte secondary battery (battery C), which has a positive electrode, a negative electrode, and a nonaqueous electrolyte, wherein the positive electrode has a positive electrode current collector and a positive electrode mixture layer attached thereon, and the positive electrode mixture layer contains a positive electrode The active material, the positive electrode active material contains lithium-containing composite oxide, the peak pore diameter of the positive electrode mixture layer is 0.7 μm or less, and the micropore volume of the positive electrode mixture layer relative to the positive electrode active material per unit weight is 0.05 cm ³ /g～0.3 cm ³ /g; the negative electrode has a negative electrode collector and a negative electrode mixture layer attached thereto, the negative electrode mixture layer contains negative electrode active materials, the negative electrode active materials contain carbon materials, and the peak micropore diameter of the negative electrode mixture layer is 0.7 μm or less. The negative electrode mixture layer has a micropore volume per unit weight of the negative electrode active material of 0.2 cm ³ /g to 0.4 ^{cm 3} /g.

The present invention further relates to an electric vehicle or a hybrid vehicle having a vehicle and a battery A, B or C mounted on the vehicle for driving the vehicle.

The invention further relates to a stationary device such as a power tool, a lift, having the device and a battery A, B or C for driving the device. The present invention also includes the case where battery A, B, or C functions as a backup power source for stationary equipment.

When fine pores with a pore diameter of 0.7 μm or less uniformly exist around the active material, it is considered that an ion supply path for supplying ions from the nonaqueous electrolyte in the separator to the periphery of the active material is sufficiently developed. Therefore, ions necessary for the charge-discharge reaction are uniformly supplied to the active material, enabling favorable charge-discharge reaction to proceed.

By setting the pore volume per unit weight of the positive electrode mixture layer to the positive electrode active material at 0.05 to 0.3 cm ³ /g, ions necessary for charge and discharge reactions are supplied to the positive electrode active material without shortage. By using such a positive electrode, a nonaqueous electrolyte secondary battery having good battery characteristics, especially good pulse output characteristics can be obtained. Therefore, a non-aqueous electrolyte secondary battery suitable for high output applications such as hybrid vehicles can be obtained.

By setting the pore volume per unit weight of the negative electrode mixture layer to 0.2 to 0.4 cm ³ /g with respect to the negative electrode active material, ions necessary for charge and discharge reactions are supplied to the negative electrode active material without shortage. By using such a negative electrode, a nonaqueous electrolyte secondary battery having good battery characteristics, especially good pulse output characteristics can be obtained. Therefore, a non-aqueous electrolyte secondary battery suitable for high output applications such as hybrid vehicles can be obtained.

Description of drawings

Fig. 1 is a schematic cross-sectional view of an example of an electrode of the present invention.

Fig. 2 is a schematic cross-sectional view of an example of a conventional electrode.

Fig. 3 is a longitudinal sectional view of an example of a cylindrical nonaqueous electrolyte secondary battery.

FIG. 4 is a schematic diagram showing patterns of charge pulses and discharge pulses applied to a battery in an experiment for obtaining a current-voltage characteristic diagram.

FIG. 5 is a schematic diagram showing current-voltage characteristics on the charging side.

Fig. 6 is a schematic diagram showing current-voltage characteristics on the discharge side.

7 is a characteristic diagram showing the relationship between the peak pore diameter of the positive electrode and the battery input value at 25° C. in the example.

8 is a characteristic diagram showing the relationship between the peak pore diameter of the negative electrode of the example and the battery output value at 25°C.

Detailed ways

The following description will be made with reference to the accompanying drawings.

Fig. 1 is a schematic cross-sectional view of an example of an electrode of the present invention. The electrode 10 has a current collector 11 and an electrode mixture layer 12 carried thereon. Active material particles 13 are filled with a certain density in electrode mixture layer 12 . Micropores (voids) 14 having a small pore diameter uniformly exist around the active material particle 13 . Such micropores 14 serve as good supply paths for supplying the nonaqueous electrolyte (ions) to the active material particles 13 .

On the other hand, FIG. 2 is a schematic cross-sectional view of an example of a conventional electrode. The electrode 20 also has a current collector 21 and an electrode mixture layer 22 attached thereto, but the electrode mixture layer 22 is filled with active material particles 23 non-uniformly. Wherein, the packing density of the active material particles 23 in the electrode mixture layer 22 is equal to the packing density of the active material particles 13 in the electrode mixture layer 12 . That is to say, the area represented by micropore 14 in FIG. 1 is equal to the area represented by micropore 24 in FIG. 2 .

In the case of FIG. 1 , micropores 14 uniformly exist around active material particles 13 . Therefore, the ions necessary for the charge-discharge reaction can be smoothly and uniformly supplied to the active material, and a good charge-discharge reaction can be performed. A nonaqueous electrolyte secondary battery using such an electrode exhibits good battery characteristics (heavy-load pulse input-output characteristics). However, the amount of nonaqueous electrolyte in the micropores varies with the volume of the micropores. If the micropore volume is small, the amount of non-aqueous electrolyte present in the micropores decreases, thereby reducing the amount of ions that contribute to charge and discharge reactions. Also, even if a necessary amount of ions is to be supplied from the side of the separator adjacent to the electrodes, the pore volume for receiving these ions is insufficient. Therefore, it is necessary to secure a pore volume above a certain level.

From the perspective that the ions necessary for the charge-discharge reaction can be smoothly and uniformly supplied to the active material, the present invention proposes the following scheme: that is, in the positive electrode, the peak pore diameter of the positive electrode mixture layer is set to be below 0.7 μm, It is preferably set to 0.5 μm or less; and the pore volume per unit weight of the positive electrode mixture layer relative to the positive electrode active material is set to 0.05 to 0.3 cm ³ /g, preferably 0.05 to 0.25 cm ³ /g. When the micropores in the positive electrode mixture layer satisfy these conditions, the micropores form a fine network and uniformly exist around the active material. Therefore, ions necessary for charge and discharge reactions are smoothly supplied to the active material through the micropores, and good heavy-duty pulse output characteristics can be obtained.

When the peak pore diameter of the positive electrode mixture layer exceeds 0.7 μm, good heavy-load pulse output characteristics cannot be obtained because the pores become non-uniform. When the pore volume per unit weight of the positive electrode mixture layer relative to the positive electrode active material is less than 0.05 cm ³ /g, ions necessary for charge and discharge reactions cannot be sufficiently supplied to the active material because the pore volume is too small. On the other hand, when the pore volume per unit weight of the positive electrode mixture layer exceeds 0.3 cm ³ /g with respect to the positive electrode active material, high capacity cannot be obtained, thereby reducing its practicality.

In addition, from the perspective that the ions necessary for the charge-discharge reaction can be smoothly and uniformly supplied to the active material, the present invention proposes the following proposal: that is, in the negative electrode, the peak pore diameter of the negative electrode mixture layer is set to 0.7 μm Below, it is preferably set to 0.5 μm or less; and the pore volume per unit weight of the negative electrode mixture layer relative to the negative electrode active material is set to 0.2 cm ³ /g to 0.4 cm ³ /g. When the micropores in the negative electrode mixture layer satisfy these conditions, the micropores form a fine network and uniformly exist around the active material. Therefore, ions necessary for charge and discharge reactions are smoothly supplied to the active material through the micropores, and good heavy-duty pulse output characteristics can be obtained.

When the peak pore diameter of the negative electrode mixture layer exceeds 0.7 μm, good heavy-load pulse output characteristics cannot be obtained. When the pore volume per unit weight of the negative electrode mixture layer relative to the negative electrode active material is less than 0.2 cm ³ /g, ions necessary for charge and discharge reactions cannot be sufficiently supplied to the active material because the pore volume is too small. On the other hand, when the pore volume per unit weight of the negative electrode mixture layer with respect to the negative electrode active material exceeds 0.4 cm ³ /g, high capacity cannot be obtained, thereby reducing its practicality.

The so-called "peak micropore diameter" is the micropore diameter when the peak value is obtained in the Log differential micropore volume distribution (representing the curve of the relationship between the Log differential micropore volume and the micropore diameter); the so-called "electrode mixture layer is relatively The "pore volume per unit weight of active material" is a value obtained by dividing the cumulative pore volume obtained by measuring a predetermined weight of an electrode mixture sample by the weight of the active material contained in the sample. In addition, the so-called Log differential micropore volume distribution refers to the value obtained by dividing the differential micropore volume dV by the logarithm of the micropore diameter D (logD), and then calculating the average micropore diameter in each interval. The resulting curves are shown in Fig.

When calculating the "peak micropore diameter" and "the micropore volume per unit weight of the electrode mixture layer relative to the active material", it must be obtained from the Log differential micropore volume distribution and the cumulative micropore volume distribution (representing the cumulative micropore volume and The curve of the relationship between the micropore diameters) excludes the distribution of micropores with a micropore diameter exceeding 5 μm. This is because the pores with a pore diameter exceeding 5 μm often include gaps between samples and gaps between the sample container and the sample when measuring the pore volume distribution using multiple samples. In the embodiment of the present invention, the possibility that micropores with a diameter exceeding 5 μm exist in the electrode mixture layer is extremely low.

The method for controlling the peak pore diameter is not particularly limited, and the following methods can be used to control the peak pore diameter, such as (i) controlling the dispersion of the active material in the electrode mixture according to the stirring degree of the electrode mixture; (ii) Prepare the electrode mixture by mixing various active substances with different particle size distributions; (iii) mix the control material (sublimation agent, etc.) of the micropore diameter in the electrode mixture, and then remove the control material from the electrode mixture layer by heating or the like; ( iv) Mixing materials soluble in non-aqueous electrolyte in the electrode mixture to control the particle size distribution of the material; (v) Covering the conductive agent around the active material in advance, and controlling the dispersion of the mixture by controlling the covering amount, etc. .

The method of controlling the micropore volume per unit weight of the electrode mixture layer relative to the active material is not particularly limited, but in addition to the above-mentioned micropore diameter control, for example, by rolling the electrode mixture layer, the active material in the electrode mixture layer is controlled. At the same time, the micropore volume per unit weight of the electrode mixture layer relative to the active material can be controlled.

The positive electrode mixture may contain various optional components in addition to the positive electrode active material which is an essential component. As an optional component, a conductive agent, a binder, a thickener, etc. are mentioned. The positive electrode mixture slurry can be obtained by mixing and kneading the positive electrode mixture and liquid components (N-methyl-2-pyrrolidone, water, etc.). At this time, according to needs, the degree of agitation of the positive electrode mixture slurry can be controlled, or a variety of active materials with different particle size distributions can be mixed in the positive electrode mixture, or a sublimation agent or a material soluble in non-aqueous electrolyte can be mixed in the positive electrode mixture slurry .

A positive electrode mixture layer having a predetermined thickness can be formed by coating the positive electrode mixture slurry on both sides of a positive electrode current collector (for example, aluminum foil), drying, and then rolling if necessary. In this case, the filling density of the positive electrode active material in the positive electrode mixture layer is preferably 2 to 3.5 g/cm ³ from the viewpoint of securing a certain pore volume. Then, the current collector is trimmed (swarfed) as necessary, whereby a sheet-shaped positive electrode of a predetermined size can be obtained.

The positive electrode active material contains a lithium-containing composite oxide capable of intercalating and deintercalating lithium. The lithium-containing composite oxide is not particularly limited, and examples thereof include lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), and lithium manganese oxide (LiMn ₂ O ₄ ). Materials in which Co, Ni, or Mn in these oxides are partially replaced by other elements (eg, Co, Ni, Mn, Al, Mg, Li, etc.) can also be preferably used. The positive electrode active material may be used alone or in combination. In particular, a preferable lithium-containing composite oxide has an average particle diameter (median particle diameter based on volume as measured by a laser diffraction particle size distribution meter: D ₅₀ ) of 2 to 20 μm, and a BET specific surface area (measured by The specific surface area measured by the BET method) is 0.2 to 1.5m ² /g, and the general formula LiNi _x M _1-x O ₂ (0<x<1, preferably 0.5≤x≤0.85, M is selected from Co , at least one of Mn, Al, Mg and Li) to represent. Such a positive electrode active material is easy to set the peak pore diameter of the positive electrode mixture layer to 0.7 μm or less, and the positive electrode mixture layer has a micropore volume per unit weight of 0.05 to 0.3 cm ³ /g relative to the positive electrode active material, so that The present invention can achieve greater effects.

The conductive agent is effective in improving the electrical conductivity of the positive electrode and making charge and discharge reactions to proceed efficiently. Carbon materials such as carbon black (for example, acetylene black (AB) and ketjen black (KB)) and graphite can be used as the conductive agent that can be contained in the positive electrode. A conductive agent may be used individually by 1 type, and may use it in combination of several types. The amount of the conductive agent contained in the positive electrode mixture is preferably 1 to 10 parts by weight per 100 parts by weight of the positive electrode active material.

The binder has the function of binding the active material particles and simultaneously binding the positive electrode mixture layer and the positive electrode current collector. As the binder that can be contained in the positive electrode, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or the like can be used. The binder may be used alone or in combination of multiple types. The amount of the binder contained in the positive electrode mixture is preferably 1 to 10 parts by weight per 100 parts by weight of the positive electrode active material.

The main function of the thickener is to adjust the viscosity of the positive electrode mixture slurry. When water is used as a liquid component to be mixed with the positive electrode mixture, a water-soluble polymer such as carboxymethylcellulose (CMC) can be used as a thickener. The amount of the thickener contained in the positive electrode mixture is preferably 0.2 to 2 parts by weight per 100 parts by weight of the positive electrode active material.

The negative electrode mixture may contain various optional components in addition to the negative electrode active material which is an essential component. As an optional component, a conductive agent, a binder, a thickener, etc. are mentioned. Negative electrode mixture slurry can be obtained by mixing and kneading the negative electrode mixture and liquid components (N-methyl-2-pyrrolidone, water, etc.). At this time, according to the needs, the stirring degree of the negative electrode mixture slurry can be controlled, or a variety of active materials with different particle size distributions can be mixed in the negative electrode mixture, or a sublimation agent or a material soluble in non-aqueous electrolyte can be mixed in the negative electrode mixture slurry .

The negative electrode mixture slurry is coated on both sides of the negative electrode current collector (such as copper foil, copper alloy foil, etc.), dried, and then rolled as necessary to form a negative electrode mixture layer with a predetermined thickness. At this time, from the viewpoint of securing a certain pore volume, the packing density of the negative electrode active material in the negative electrode mixture layer is preferably 1 to 1.5 g/cm ³ . Then, the current collector is trimmed (swarfed) as necessary, whereby a sheet-shaped negative electrode of a predetermined size can be obtained.

The negative electrode active material contains a carbon material capable of intercalating and deintercalating lithium. The carbon material is not particularly limited, and examples thereof include graphite (natural graphite, artificial graphite, etc.), coke, and the like. In particular, it is preferable to use graphite having an average particle diameter (median particle diameter based on volume as measured by a laser diffraction particle size distribution meter: D ₅₀ ) of 2 to 20 μm and a BET specific surface area of 2 to 6 m ² /g. Such negative electrode active material is easy to set the peak micropore diameter of the negative electrode mixture layer to be below 0.7 μm, and the micropore volume of the negative electrode mixture layer relative to the negative electrode active material per unit weight is set to 0.2～0.4cm ³ /g, thereby The present invention can achieve greater effects.

From the viewpoint of controlling the pore volume distribution as described above, it is more preferable to use graphite (graphite X) with an average particle diameter of 10 to 30 μm and a BET specific surface area of 0.5 to 6 m ² /g in combination with an average particle diameter of 2 to 8 μm and a BET Graphite (graphite Y) having a specific surface area of 2 to 20 m ² /g. The weight ratio of graphite X:graphite Y is preferably in the range of X:Y=100:0 to X:Y=50:50.

As the negative electrode binder, for example, styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), or the like can be used. The binder may be used alone or in combination of multiple types. The amount of the binder contained in the negative electrode mixture is preferably 1 to 10 parts by weight per 100 parts by weight of the negative electrode active material.

Water-soluble polymers such as carboxymethylcellulose (CMC) can also be used as the negative electrode thickener. The amount of the thickener contained in the negative electrode mixture is preferably 0.2 to 2 parts by weight per 100 parts by weight of the negative electrode active material.

The nonaqueous electrolyte secondary battery of the present invention has the above-mentioned positive electrode and/or the above-mentioned negative electrode. A separator is usually placed between the positive and negative electrodes. The role of the separator is to insulate the positive electrode and the negative electrode while maintaining the non-aqueous electrolyte. As the separator, a porous film made of polyolefin resin is preferably used. For example, a porous film made of polyethylene (PE), a porous film made of polypropylene (PP), or a laminated product of a porous film made of PE and a porous film made of PP is used.

The nonaqueous electrolyte contains a nonaqueous solvent in which a lithium salt is dissolved. The concentration of the lithium salt in the non-aqueous electrolyte is preferably 0.5 to 2 mol/dm ³ .

As non-aqueous solvents, for example, cyclic carbonates such as ethylene carbonate (EC) and propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) are preferably used. Equal chain carbonates, etc. One type of nonaqueous solvent may be used alone, but it is preferable to use a mixture of two or more types. Preferably, 0 to 50% by weight of the entire non-aqueous solvent is cyclic carbonate, and 50 to 90% by weight is chain carbonate.

As the lithium salt, lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), and the like are preferably used. Lithium salts may be used alone or in combination.

The shape of the non-aqueous electrolyte secondary battery to which the present invention can be applied is not particularly limited, and it can be applied to batteries of various shapes such as cylindrical, square, and laminated, for example. Make the electrode group with the separator interposed between the positive electrode and the negative electrode, store the electrode group in the battery case, inject non-aqueous electrolyte into the battery case, and seal the battery case to complete the production of the battery.

Hereinafter, the present invention will be specifically described based on examples. In addition, Examples 1 to 21 and Reference Examples 1 to 11 are examples and reference examples of the invention related to the positive electrode. Examples 22 to 24 and Reference Examples 12 to 17 are examples and reference examples of the invention related to the negative electrode. The batteries of Reference Examples 1 to 11 of the invention relating to the positive electrode correspond to examples of the invention of the non-aqueous electrolyte secondary battery because they contain the negative electrode of the present invention. The batteries of Reference Examples 12 to 17 of the invention relating to the negative electrode correspond to examples of the invention of the non-aqueous electrolyte secondary battery because they contain the positive electrode of the present invention.

Example 1

In this example, a 17500 type cylindrical lithium ion secondary battery was produced.

[making of positive electrode]

(i) Preparation of positive electrode active material

A lithium-nickel composite oxide represented by the composition formula LiNi _0.7 Co _0.2 Al _0.1 O ₂ can be formulated as the positive electrode active material. In the NiSO ₄ aqueous solution, a predetermined amount of Co and Al sulfate was added to prepare a saturated aqueous solution. While stirring this saturated aqueous solution, an alkaline aqueous solution in which sodium hydroxide was dissolved was slowly added dropwise thereto. By such co-precipitation method, a precipitate of ternary system nickel hydroxide (Ni _0.7 Co _0.2 Al _0.1 (OH) ₂ ) is produced. The generated precipitate was filtered, washed with water, and dried at 80°C. The average particle diameter of Ni _0.7 Co _0.2 Al _0.1 (OH) ₂ is 10 μm.

The obtained Ni _0.7 Co _0.2 Al _0.1 (OH) ₂ was heat-treated at 900° C. for 10 hours in the air to obtain nickel oxide (Ni _0.7 Co _0.2 Al _0.1 O). As a result of analyzing the obtained Ni _0.7 Co _0.2 Al _0.1 O by powder X-ray diffraction, it was confirmed that Ni _0.7 Co _0.2 Al _0.1 O was single-phase nickel oxide.

To Ni _0.7 Co _0.2 Al _0.1 O, lithium hydroxide monohydrate was added and mixed so that the sum of the atomic numbers of Ni, Co, and Al was equal to the atomic number of Li. This mixture was heat-treated at 800° C. for 10 hours in dry air, whereby the target LiNi _0.7 Co _0.2 Al _0.1 O ₂ was obtained. As a result of analyzing the obtained lithium-nickel composite oxide by powder X-ray diffraction, it was confirmed that the lithium-nickel composite oxide has a single-phase hexagonal layered structure. It was also confirmed that Co and Al were trapped in the crystal structure of LiNiO ₂ , and the lithium-nickel composite oxide was formed as a solid solution. The lithium nickel composite oxide was pulverized and classified to obtain a positive electrode active material having an average particle diameter (D ₅₀ ) of 9.5 μm and a BET specific surface area of 0.5 m ² /g.

(ii) Preparation of positive electrode mixture slurry

With 90 parts by weight of the positive electrode active material, 5 parts by weight of acetylene black as a conductive agent, and 5 parts by weight of polyvinylidene fluoride (PVDF) as a binder (the NMP solution of PVDF produced by Kureha Chemical Industry Co., Ltd. "KF Polymer #1320 (trade name) "42 parts by weight) and an appropriate amount of N-methyl-2-pyrrolidone (NMP) are mixed, and carry out the mixing of 60 minutes in the mixing equipment, just allocate the solid content to be 50 % by weight of positive electrode mixture slurry. At this time, the premixing of the powder was started, and the NMP solution of PVDF and all the NMP were put into the obtained powder mixture. The mixing equipment uses a planetary mixer produced by Tokuji Chemical Industry Co., Ltd. The revolution speed of the planetary mixer was set to 50 rpm. The degree of dispersion of the positive electrode mixture changes with the mixing time. It is generally believed that the longer the mixing time, the higher the degree of dispersion of the positive electrode mixture.

(iii) Preparation of positive electrode

Alloy IN30 (tempered H18, thickness 20 μm) was used for the positive electrode current collector. Alloy IN30 contains 99.3% by weight of Al, and the balance is composed of Si, Fe, Cu, Mn, Mg, and Zn. The positive electrode mixture slurry was applied to both surfaces of the positive electrode current collector and dried. Then, the positive electrode mixture was rolled so that the density of the positive electrode mixture was 2.8 g/cm ³ , thereby forming positive electrode mixture layers each having a thickness of 30 μm on both surfaces of the positive electrode current collector. Then, chipping was performed on the positive electrode current collector to obtain a positive electrode having a thickness of 80 μm, a width of 37 mm, and a length of 450 mm.

[2] Production of negative electrode

(i) Preparation of negative electrode active material

As the negative electrode active material, artificial graphite with an average particle diameter (D ₅₀ ) of 10 μm and a BET specific surface area of 4.8 m ² /g was used.

(ii) Preparation of negative electrode mixture slurry

96 parts by weight of the negative electrode active material, 3 parts by weight of SBR (the aqueous dispersion of SBR "BM400B (trade name)" 7.5 parts by weight produced by Zeon (Japan) as a binder), 1 part by weight as a thickener The CMC and appropriate amount of water were mixed, and then mixed in a mixing equipment for 90 minutes to prepare a negative electrode mixture slurry with a solid content of 40% by weight. At this time, dry mixing of graphite and CMC powder was started, and all of the SBR aqueous dispersion and water were put into the obtained powder mixture. As the kneading equipment, a planetary mixer produced by Tokuji Kagaku Kogyo Co., Ltd. used in the production of positive electrodes was used. The revolution speed of the planetary mixer was set to 50 rpm.

(iii) Preparation of negative electrode

Copper foil (thickness: 10 μm) was used for the negative electrode current collector. The negative electrode mixture slurry was applied to both surfaces of the negative electrode current collector and dried. Then, the negative electrode mixture was rolled so that the density of the negative electrode mixture was 1.2 g/cm ³ , thereby forming negative electrode mixture layers each having a thickness of 30.5 μm on both surfaces of the negative electrode current collector. Then, chipping was performed on the negative electrode current collector to obtain a negative electrode having a thickness of 81 μm, a width of 39 mm, and a length of 470 mm.

[3] Preparation of non-aqueous electrolyte

In a mixed non-aqueous solvent with a volume ratio of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) of 1:3, dissolve LiPF ₆ as a lithium salt at a concentration of 1.0 mol/ ^dm3 to obtain a non-aqueous electrolyte.

[4] Production of battery

An aluminum lead was welded to the positive electrode current collector, and then the positive electrode was introduced into a drying oven for the purpose of removing residual water, and dried at 100° C. for 10 hours in a dry atmosphere. A lead made of nickel was welded to the negative electrode current collector, and then the negative electrode was introduced into a drying oven for the purpose of removing residual water, and dried at 80° C. for 10 hours in a dry atmosphere.

A cylindrical battery having the structure shown in FIG. 3 was assembled in the following manner.

The dried positive electrode 31 and negative electrode 32 were wound together with a separator 33 made of a polyethylene porous film having a thickness of 25 μm interposed therebetween, thereby producing an electrode group. The upper insulating plate 36 is arranged on the upper surface of the electrode group, and the lower insulating plate 37 is arranged on the lower surface, and then the electrode group is inserted into a nickel-plated iron battery case 38 . The negative electrode lead 35 is welded to the inner bottom of the battery case 38 by resistance welding. The positive electrode lead 34 is welded to the back of the sealing plate 39 by laser welding, so that the positive electrode terminal 30 and the positive electrode lead 34 are conducted. The non-aqueous electrolyte is injected into the battery case 38, and then the opening of the battery case 38 is sealed with a sealing plate 39, and the battery is completed.

Example 2

A battery was fabricated in the same manner as in Example 1, except that the mixing time of the slurry with a planetary mixer was set to 90 minutes when preparing the positive electrode mixture slurry.

Example 3

A battery was fabricated in the same manner as in Example 1, except that the mixing time of the slurry with a planetary mixer was set to 120 minutes when preparing the positive electrode mixture slurry.

Example 4

A battery was produced in the same manner as in Example 1, except that the mixing time of the slurry with a planetary mixer was set to 150 minutes when preparing the positive electrode mixture slurry.

Example 5

A battery was produced in the same manner as in Example 1, except that the mixing time of the slurry with a planetary mixer was set to 180 minutes when preparing the positive electrode mixture slurry.

"Reference Example 1"

A battery was fabricated in the same manner as in Example 1, except that the mixing time of the slurry with a planetary mixer was set to 30 minutes when preparing the positive electrode mixture slurry.

"Reference Example 2"

A battery was fabricated in the same manner as in Example 3, except that the positive electrode mixture was rolled so that the density of the positive electrode mixture was 3.5 g/cm ³ , and positive electrode mixture layers each having a thickness of 24 μm were formed on both surfaces of the positive electrode collector.

"Reference Example 3"

A battery was fabricated in the same manner as in Reference Example 2, except that the mixing time of the slurry with a planetary mixer was set to 150 minutes when preparing the positive electrode mixture slurry.

"Reference Example 4"

A battery was fabricated in the same manner as in Reference Example 2, except that the mixing time of the slurry with a planetary mixer was set to 180 minutes when preparing the positive electrode mixture slurry.

"Reference Example 5"

A battery was fabricated in the same manner as in Example 3, except that the positive electrode mixture was rolled so that the density of the positive electrode mixture was 3.4 g/cm ³ , and positive electrode mixture layers each having a thickness of 25 μm were formed on both sides of the positive electrode collector.

"Reference Example 6"

A battery was fabricated in the same manner as in Reference Example 5, except that the mixing time of the slurry with a planetary mixer was set to 150 minutes when preparing the positive electrode mixture slurry.

"Reference Example 7"

A battery was fabricated in the same manner as in Reference Example 5, except that the mixing time of the slurry with a planetary mixer was set to 180 minutes when preparing the positive electrode mixture slurry.

Example 6

A battery was fabricated in the same manner as in Example 1, except that the positive electrode mixture was rolled so that the density of the positive electrode mixture was 3.3 g/cm ³ , and positive electrode mixture layers each having a thickness of 25.5 μm were formed on both sides of the positive electrode current collector.

Example 7

A battery was fabricated in the same manner as in Example 6, except that the mixing time of the slurry with a planetary mixer was set to 90 minutes when preparing the positive electrode mixture slurry.

Example 8

A battery was produced in the same manner as in Example 6, except that the mixing time of the slurry with a planetary mixer was set to 120 minutes when preparing the positive electrode mixture slurry.

Example 9

A battery was produced in the same manner as in Example 6, except that the mixing time of the slurry with a planetary mixer was set to 150 minutes when preparing the positive electrode mixture slurry.

Example 10

A battery was produced in the same manner as in Example 6, except that the mixing time of the slurry with a planetary mixer was set to 180 minutes when preparing the positive electrode mixture slurry.

"Reference Example 8"

A battery was fabricated in the same manner as in Example 6, except that the mixing time of the slurry with a planetary mixer was set to 30 minutes when preparing the positive electrode mixture slurry.

Example 11

A battery was fabricated in the same manner as in Example 1, except that the positive electrode mixture was rolled so that the density of the positive electrode mixture was 3.0 g/cm ³ , and positive electrode mixture layers each having a thickness of 28 μm were formed on both surfaces of the positive electrode collector.

Example 12

A battery was fabricated in the same manner as in Example 11, except that the mixing time of the slurry with a planetary mixer was set to 90 minutes when preparing the positive electrode mixture slurry.

Example 13

A battery was fabricated in the same manner as in Example 11, except that the mixing time of the slurry with a planetary mixer was set to 120 minutes when preparing the positive electrode mixture slurry.

Example 14

A battery was fabricated in the same manner as in Example 11, except that the mixing time of the slurry with a planetary mixer was set to 150 minutes when preparing the positive electrode mixture slurry.

Example 15

A battery was fabricated in the same manner as in Example 11, except that the mixing time of the slurry with a planetary mixer was set to 180 minutes when preparing the positive electrode mixture slurry.

"Reference Example 9"

A battery was fabricated in the same manner as in Example 11, except that the mixing time of the slurry with a planetary mixer was set to 30 minutes when preparing the positive electrode mixture slurry.

"Reference Example 10"

A battery was fabricated in the same manner as in Example 1, except that the positive electrode mixture was rolled so that the density of the positive electrode mixture was 2.0 g/cm ³ , and positive electrode mixture layers each having a thickness of 35.5 μm were formed on both sides of the positive electrode current collector.

Example 16

A battery was fabricated in the same manner as in Reference Example 10, except that the mixing time of the slurry with a planetary mixer was set to 90 minutes when preparing the positive electrode mixture slurry.

Example 17

A battery was produced in the same manner as in Reference Example 10, except that the mixing time of the slurry with a planetary mixer was set to 120 minutes when preparing the positive electrode mixture slurry.

Example 18

A battery was fabricated in the same manner as in Reference Example 10, except that the mixing time of the slurry with a planetary mixer was set to 150 minutes when preparing the positive electrode mixture slurry.

Example 19

A battery was fabricated in the same manner as in Reference Example 10, except that the mixing time of the slurry with a planetary mixer was set to 180 minutes when preparing the positive electrode mixture slurry.

"Reference Example 11"

A battery was fabricated in the same manner as in Reference Example 10, except that the mixing time of the slurry with a planetary mixer was set to 30 minutes when preparing the positive electrode mixture slurry.

Example 20

As the positive electrode active material, a positive electrode active material A with an average particle diameter (D ₅₀ ) of 15 μm and a BET specific surface area of 0.3 m ² /g mixed with a weight ratio of positive electrode active material A: positive electrode active material B = 75:25 and an average A battery was produced in the same manner as in Example 1 except that the mixture obtained by the positive electrode active material B had a particle diameter (D ₅₀ ) of 5 μm and a BET specific surface area of 0.95 m ² /g.

The positive electrode active material A and the positive electrode active material B were prepared according to the same procedure as the positive electrode active material (LiNi _0.7 Co _0.2 Al _0.1 O ₂ ) in Example 1. However, when nickel hydroxide is produced by the coprecipitation method, the stirring state and temperature of the saturated aqueous solution are changed to control the average particle diameter and BET specific surface area of the positive electrode active material A and the positive electrode active material B as described above.

Example 21

As the positive electrode active material, a battery was fabricated in the same manner as in Example 20, except that a mixture obtained by mixing positive electrode active material A:positive electrode active material B=40:60 was used.

[evaluate]

(Determination of Micropore Volume Distribution)

For the positive electrodes of each example and reference example, the micropore volume distribution of the positive electrode mixture layer was measured using a mercury porosimeter. As the porosimeter, "Autopore III 9410" manufactured by Shimadzu Corporation was used. Here, the cumulative pore volume distribution and the Log differential pore volume distribution were obtained.

<peak pore diameter>

The pore distribution with pore diameters below 5 μm was extracted from the Log differential pore volume distribution (those with pore diameters exceeding 5 μm were excluded) to calculate the peak pore diameter.

<Pore volume per unit weight of positive electrode active material>

Extract the micropore distribution with a micropore diameter below 5 μm from the cumulative micropore volume distribution (excluding the micropore distribution with a micropore diameter exceeding 5 μm), and divide the cumulative micropore volume by the weight of the positive electrode active material contained in the sample , the micropore volume per unit weight of the positive electrode active material is calculated.

(battery capacity)

The batteries of each example and reference example were charged and discharged at a constant current of 70mA under the conditions of a charging upper limit voltage of 4.2V and a discharging lower limit voltage of 3.0V in an environment of 25°C to confirm the battery capacity. As a result, the battery capacity of each Example and the reference example was about 350 mAh.

(Battery input and output characteristics)

The input/output characteristics of the batteries of the respective examples and reference examples were evaluated in the following procedure. In an environment of 25° C., each battery was charged to a state of charge of 60% at a constant current, and then left to stand in an environment of 25° C. for 1 hour. Then, using the graph shown in FIG. 4 , 10-second charge pulses and discharge pulses of constant current were alternately applied to the battery with a 1-minute pause in the middle. At this time, the current value was increased stepwise in the range of 0.35 to 20 A, and the battery voltage at 10 seconds after application of each pulse was measured. Through this test, the relationship between the current value when the pulse on the charge side was applied and the battery voltage at 10 seconds after the pulse application was obtained (the current-voltage characteristic diagram on the charge side shown in FIG. 5 ). Similarly, the relationship between the current value when the pulse on the discharge side was applied and the battery voltage at 10 seconds after the pulse application was obtained (the current-voltage characteristic diagram on the discharge side shown in FIG. 6 ).

Calculate the current value when the battery voltage is 4.2V from the current-voltage characteristic diagram on the charging side, and then calculate the input value from the product of these voltage values and current values.

Calculate the current value when the battery voltage is 2.5V from the current-voltage characteristic diagram on the discharge side, and then calculate the output value from the product of these voltage values and current values.

The mixture density, peak pore diameter, positive electrode mixture layer relative to the pore volume per unit weight of the positive electrode active material of the positive electrodes of Examples 1-20 and Reference Examples 1-11 and the output value of the battery at 25°C are shown in the table 1.

The relationship between the peak pore diameter and the output value of the battery relating to Examples 1 to 20 and Reference Examples 1 to 11 is shown in FIG. 7 .

Table 1

Mixture density (g/cm ³ ) Peak pore diameter (μm) Micropore volume per unit weight of active substance (cm ³ /g) Output value at 25°C (W) Example 1 2.8 0.70 0.114 25 Example 2 2.8 0.60 0.113 26 Example 3 2.8 0.49 0.115 29 Example 4 2.8 0.40 0.112 31 Example 5 2.8 0.31 0.110 31 Reference example 1 2.8 0.93 0.114 twenty three Reference example 2 3.5 0.41 0.035 19 Reference example 3 3.5 0.34 0.038 19 Reference example 4 3.5 0.26 0.040 18 Reference example 5 3.4 0.42 0.044 20 Reference example 6 3.4 0.35 0.046 twenty one Reference example 7 3.4 0.26 0.043 twenty one Example 6 3.3 0.69 0.054 twenty three Example 7 3.3 0.53 0.052 twenty four Example 8 3.3 0.43 0.051 26 Example 9 3.3 0.36 0.057 26 Example 10 3.3 0.27 0.050 25 Reference example 8 3.3 0.82 0.053 twenty one Example 11 3.0 0.70 0.088 twenty three Example 12 3.0 0.58 0.086 twenty four Example 13 3.0 0.47 0.090 27 Example 14 3.0 0.38 0.088 29 Example 15 3.0 0.29 0.082 29 Reference example 9 3.0 0.89 0.092 twenty two Reference example 10 2.0 0.83 0.308 25 Example 16 2.0 0.68 0.297 27 Example 17 2.0 0.60 0.298 30 Example 18 2.0 0.49 0.300 32 Example 19 2.0 0.36 0.296 33 Reference example 11 2.0 0.95 0.299 34 Example 20 2.8 0.31 0.113 32 Example 21 2.8 0.27 0.111 35

It can be seen from Table 1 and FIG. 7 that the output of the battery increases when the peak pore diameter is 0.7 μm or less. Also in Examples 6 to 10 and Examples 11 to 15, it was seen that the smaller the peak pore diameter, the more the output increased. Especially when the peak micropore diameter is below 0.5 μm, the output of the battery is greatly increased.

In Figure 7, positive electrodes with the same mixture density (that is, the same pore volume per unit weight of the positive electrode mixture layer relative to the positive electrode active material) and different peak pore diameters are compared with each other, indicating that when the peak pore diameter When reduced, the output of the battery slowly increases. When the peak pore diameter is 0.7 μm or less, and further 0.5 μm or less, the tendency for the output to increase is greater. This is presumably because the supply path for supplying ions from the non-aqueous electrolyte in the separator to the positive electrode active material is constructed in an optimized state in the positive electrode.

When micropores with a pore diameter of 0.7 μm or less are uniformly present around the active material, ion paths for supplying ions from the nonaqueous electrolyte in the separator to the active material are everywhere. Therefore, ions necessary for charge and discharge reactions can be smoothly and uniformly supplied to the active material. Therefore, it is considered that a good charge-discharge reaction can be performed, and the non-aqueous electrolyte secondary battery exhibits good battery characteristics.

Even if the peak pore diameter is 0.7 μm or less, as in Reference Examples 2 to 7, when the pore volume per unit weight of the positive electrode mixture layer relative to the positive electrode active material is less than 0.05 cm ³ /g, the output of the battery Features are low. On the other hand, as in Examples 16 to 19, when the pore volume is in the range of 0.05 to 0.3 cm ³ /g, and further 0.05 to 0.25 cm ³ /g, good output characteristics can also be obtained.

It is generally believed that the cumulative micropore volume is related to the number of ion supply paths. When the cumulative pore volume is small, ions are insufficient, so that the active material cannot be supplied with the number of ions required for charge and discharge reactions. Therefore, it is generally considered that a certain or more pore volume is necessary. From the results in Table 1, it can be considered that the positive electrode mixture layer must have a pore volume per unit weight of 0.05 cm ³ /g or more relative to the positive electrode active material.

Just like Examples 20-21, even under the situation of mixing positive electrode active materials with different average particle diameters, the peak pore diameter of the positive electrode mixture layer and the micropore size per unit weight of the positive electrode mixture layer relative to the positive electrode active material can be controlled. Pore volume. Furthermore, the batteries of Examples 20 to 21 all showed good output characteristics.

In addition, the reason why Table 1 shows only the output values is because the output values varied greatly between Examples 1 to 20 and Reference Examples 1 to 11. The reason for this is considered to be that the movement of ions in the positive electrode becomes a dominant factor in the short-time output pulse.

Example 22

As the negative electrode active material, a negative electrode active material C (man-made) with a mixed average particle diameter (D ₅₀ ) of 15 μm and a BET specific surface area of 3.2 m ² /g was used in a weight ratio of positive electrode active material C: positive electrode active material D=75:25. Graphite) and a negative electrode active material D (artificial graphite) having an average particle diameter (D ₅₀ ) of 5 μm and a BET specific surface area of 9.6 m ² /g, a battery was produced in the same manner as in Example 1.

"Reference Example 12"

A battery was fabricated in the same manner as in Example 1, except that the mixing time of the slurry with the planetary mixer was set to 60 minutes when preparing the negative electrode mixture slurry.

"Reference Example 13"

A battery was fabricated in the same manner as in Example 1, except that the mixing time of the slurry with a planetary mixer was set to 30 minutes when preparing the negative electrode mixture slurry.

Example 23

A battery was produced in the same manner as in Example 1, except that the negative electrode mixture was rolled to have a density of 1.5 g/cm ³ to form negative electrode mixture layers with a thickness of 29 μm on both sides of the negative electrode collector.

Example 24

A battery was produced in the same manner as in Example 22, except that the negative electrode mixture was rolled so that the density of the negative electrode mixture was 1.5 g/cm ³ , and negative electrode mixture layers each having a thickness of 29 μm were formed on both sides of the negative electrode collector.

"Reference Example 14"

A battery was produced in the same manner as in Reference Example 12, except that the negative electrode mixture was rolled to have a density of 1.5 g/cm ³ to form negative electrode mixture layers each having a thickness of 29 μm on both sides of the negative electrode collector.

"Reference Example 15"

A battery was produced in the same manner as in Reference Example 13, except that the negative electrode mixture was rolled so that the density of the negative electrode mixture was 1.5 g/cm ³ , and negative electrode mixture layers each having a thickness of 29 μm were formed on both sides of the negative electrode collector.

"Reference Example 16"

A battery was produced in the same manner as in Example 22, except that the negative electrode mixture was rolled so that the density of the negative electrode mixture was 1.6 g/cm ³ , and negative electrode mixture layers each having a thickness of 27 μm were formed on both sides of the negative electrode collector.

"Reference Example 17"

A battery was fabricated in the same manner as in Reference Example 12 except that the negative electrode mixture was rolled to have a density of 1.6 g/cm ³ to form negative electrode mixture layers each having a thickness of 27 μm on both sides of the negative electrode collector.

Table 2 shows the peak pore diameters, the pore volume per unit weight of the negative electrode active material, and the input values of the batteries in Examples 22 to 24 and Reference Examples 12 to 17.

The relationship between the peak pore diameter and the input value of the battery relating to Examples 22 to 24 and Reference Examples 12 to 17 is shown in FIG. 8 .

Table 2

Mixture density (g/cm ³ ) Peak micropore diameter (μm) Micropore volume per unit weight of active substance (cm ³ /g) Input value at 25°C (W) Example 1 1.2 0.69 0.400 27 Example 22 1.2 0.5 0.398 29 Reference example 12 1.2 1.00 0.402 25 Reference example 13 1.2 1.20 0.403 25 Example 23 1.5 0.66 0.210 25 Example 24 1.5 0.48 0.208 26 Reference example 14 1.5 0.95 0.215 twenty four Reference example 15 1.5 1.10 0.207 twenty three Reference example 16 1.6 0.53 0.172 twenty one Reference example 17 1.6 0.89 0.167 20

As can be seen from Table 2 and FIG. 8 , as in the case of the positive electrode, when the peak pore diameter is 0.7 μm or less, and further 0.5 μm or less, the input value of the battery is large. However, as in Reference Examples 16 to 17, when the pore volume per unit weight of the negative electrode mixture layer relative to the negative electrode active material is less than 0.2 cm ³ /g, even if the peak pore diameter is 0.7 μm or less, the battery performance The input value is also lower.

It is considered that such a result is obtained because, as in the case of the positive electrode, since micropores with a pore diameter of 0.7 μm or less exist uniformly around the active material, ions are supplied from the nonaqueous electrolyte in the separator to the active material. Ion paths are everywhere. Therefore, it is considered that the ions necessary for the charge-discharge reaction can be smoothly and uniformly supplied to the active material, so that a good charge-discharge reaction can be performed, and the non-aqueous electrolyte secondary battery exhibits good battery characteristics.

In Fig. 8, negative electrodes with the same mixture density (that is, the same micropore volume per unit weight of the negative electrode mixture layer relative to the negative active material) and different peak pore diameters are compared with each other, indicating that when the peak pore diameter When reduced, the output of the battery slowly increases. When the peak pore diameter is less than 0.7 μm, and further less than 0.5 μm, the tendency of the input to increase increases. The reason for this is presumed to be that the path for supplying ions from the non-aqueous electrolyte in the separator to the negative electrode active material is constructed in an optimized state in the negative electrode.

As in the case of the positive electrode, it is generally considered that the cumulative pore volume correlates with the number of ion supply paths. When the cumulative pore volume is small, ions are insufficient, so that the active material cannot be supplied with the number of ions required for charge and discharge reactions. Therefore, it is generally considered that a certain or more pore volume is necessary. From the results in Table 2, it can be considered that the negative electrode mixture layer must have a micropore volume per unit weight of 0.2 cm ³ /g or more relative to the negative electrode active material. In addition, it can be seen from Table 2 that good battery characteristics can be obtained when the pore volume per unit weight of the negative electrode mixture layer relative to the negative electrode active material is in the range of up to 0.4 cm ³ /g.

The present invention can be suitably applied to non-aqueous electrolyte secondary batteries requiring high input-output characteristics. For example, in Examples 1 to 24 of the present invention, if the size of the positive electrode or the negative electrode is changed, the design capacity can be changed to, for example, 2 Ah or more. Such a battery can expect high output and input characteristics, and can be used as a power source for mobile vehicles such as strong hybrid or weak hybrid vehicles, electric vehicles, and electric bicycles that run on the power of both internal combustion engines or fuel cells and electric motors (motors, etc.). Such a battery is suitable even as an auxiliary driving power source for a hybrid vehicle, used to drive various devices in the vehicle; or it can give the engine a boost when the car starts, starts or accelerates; and when the vehicle decelerates , can effectively input regenerative energy. The battery of the present invention is further applicable to a power supply for electric tools, a power supply for fixed equipment such as lifts, etc., and can drive and boost these tools and equipment, and can effectively input regenerative energy.

Claims (10)

1. positive electrode for nonaqueous electrolyte secondary battery, it has the positive electrode collector and the anode mixture layer of appendix thereon, wherein,

Described anode mixture layer contains positive active material, and described positive active material contains lithium-contained composite oxide,

The peak value micro-pore diameter of described anode mixture layer is below the 0.7 μ m,

Described anode mixture layer is 0.05cm with respect to the micropore volume of the per unit weight of described positive active material ³/ g～0.3cm ³/ g.

2. positive electrode for nonaqueous electrolyte secondary battery according to claim 1, wherein, described peak value micro-pore diameter is below the 0.5 μ m.

3. rechargeable nonaqueous electrolytic battery, it has the described positive electrode for nonaqueous electrolyte secondary battery of claim 1, negative pole and nonaqueous electrolyte.

4. anode for nonaqueous electrolyte secondary battery, it has the negative electrode collector and the anode mixture layer of appendix thereon, wherein,

Described anode mixture layer contains negative electrode active material, and described negative electrode active material contains carbon materials,

The peak value micro-pore diameter of described anode mixture layer is below the 0.7 μ m,

Described anode mixture layer is 0.2cm with respect to the micropore volume of the per unit weight of described negative electrode active material ³/ g～0.4cm ³/ g.

5. anode for nonaqueous electrolyte secondary battery according to claim 4, wherein, described peak value micro-pore diameter is below the 0.5 μ m.

6. rechargeable nonaqueous electrolytic battery, it has positive pole, the described anode for nonaqueous electrolyte secondary battery of claim 4 and nonaqueous electrolyte.

7. electric automobile or hybrid vehicle, it has vehicle and is used to drive described vehicle and is loaded in claim 3 or 6 described rechargeable nonaqueous electrolytic batteries on the described vehicle.

8. electric tool or stationary device, claim 3 or 6 described rechargeable nonaqueous electrolytic batteries that it has equipment and is used to drive described equipment.

9. electric automobile or hybrid vehicle, it has vehicle and is used to drive described vehicle and is loaded in rechargeable nonaqueous electrolytic battery on the described vehicle,

Described rechargeable nonaqueous electrolytic battery has positive pole, negative pole and nonaqueous electrolyte, wherein,

Described just having the positive electrode collector and an anode mixture layer of appendix thereon,

Described anode mixture layer contains positive active material, and described positive active material contains lithium-contained composite oxide,

The peak value micro-pore diameter of described anode mixture layer is below the 0.7 μ m,

Described anode mixture layer is 0.05cm with respect to the micropore volume of the per unit weight of described positive active material ³/ g～0.3cm ³/ g,

Described negative pole has the negative electrode collector and the anode mixture layer of appendix thereon,

Described anode mixture layer contains negative electrode active material, and described negative electrode active material contains carbon materials,

The peak value micro-pore diameter of described anode mixture layer is below the 0.7 μ m,

Described anode mixture layer is 0.2cm with respect to the micropore volume of the per unit weight of described negative electrode active material ³/ g～0.4cm ³/ g.

10. electric tool or stationary device, the rechargeable nonaqueous electrolytic battery that it has equipment and is used to drive described equipment,

Described rechargeable nonaqueous electrolytic battery has positive pole, negative pole and nonaqueous electrolyte, wherein,

Described just having the positive electrode collector and an anode mixture layer of appendix thereon,

Described anode mixture layer contains positive active material, and described positive active material contains lithium-contained composite oxide,

The peak value micro-pore diameter of described anode mixture layer is below the 0.7 μ m,

Described anode mixture layer is 0.05cm with respect to the micropore volume of the per unit weight of described positive active material ³/ g～0.3cm ³/ g,

Described negative pole has the negative electrode collector and the anode mixture layer of appendix thereon,

Described anode mixture layer contains negative electrode active material, and described negative electrode active material contains carbon materials,

The peak value micro-pore diameter of described anode mixture layer is below the 0.7 μ m,

Described anode mixture layer is 0.2cm with respect to the micropore volume of the per unit weight of described negative electrode active material ³/ g～0.4cm ³/ g.

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